In a conventional quantitative powder and granular material feeder, an inner tube for feeding a powder and granular material is provided on a bottom plate through an intermediation of a clearance, and a lower end of an outer tube sharing the same center line with the inner tube is connected to the bottom plate; an annular passage for the powder and granular material discharged through the clearance is formed between the inner and outer tubes, and a discharge port is provided in the passage; central rotary blades (spokes) are provided on an upright rotary member protruding from the central portion of the bottom plate; and an outer peripheral rotary ring is provided at distal ends of the spokes to extend along an inner peripheral surface of the outer tube, and a plurality of inward claws are provided on the rotary ring, the material being discharged in a quantitative manner through the discharge port (see, for example, Patent Documents 1 and 2).
For hygroscopic powder and granular materials (e.g., slaked lime and active carbon), there has been devised a means by which a rotor rotating on the still outer side of the discharge port and the passage is provided on a supporting plate, and a plurality of powder/granular material accommodating cutout boxes are formed at equal intervals in the outer peripheral portion of the rotor, the hygroscopic powder and granular material in the boxes being discharged by utilizing self-weight descent of a floating roller or a floating ball (see, e.g., Patent Document 3).
In a case of a powder and granular materials containing water and exhibiting poor fluidity (e.g., a material such as titanium oxide, powder dye, pigment, soda ash, zeolite, or toner; a food such as starch, amino acid, or flour; or dehydrated cake plaster of sludge, or fertilizer), the material cannot be accommodated in the cutout boxes situated directly below the discharge port of the passage to a sufficient degree due to the poor fluidity, so the quantitative feeding using the cutout boxes is conducted rather insufficiently; thus there is a demand for an improvement in this regard (see, e.g., Patent Document 3).
Patent Document 1: Japanese Utility Model Examined Publication No. Hei 06-47860 (Japanese Utility Model Application Laid-open No. Hei 03-130237)
Patent Document 2: JP 3139903 A (JP 07-187405 A)
Patent Document 3: JP 3401233 A (JP 2002-2965 A)